As is well known, the knee joint, although frequently considered a hinge joint, actually comprises two joints, lateral and medial, between the femur and tibia, and one arthrodial joint between the patella and femur. The primary movements of the knee comprise flexion, i.e., rearward rotational movement of the tibia relative the femur, and extension, i.e. forward rotational movement of the tibia relative the femur.
The flexion and extension movements of the knee joint are not simply pivotal movements about a fixed axis. During flexion, the axis around which movement takes place shifts backward, and during extension it shifts forward. This is different from a more typical hinge joint, such as an elbow, where the axis of rotation does not shift. As full extension is reached, the tibia is rotated inward or rearward and the joint in effect is disposed in a "locked" position with the ligaments taut. This gives the joint greater stability in the extended position. As flexion is initiated, the tibia initially lowers or moves downwardly with the small external rotation of the tibia which "unlooks" the joint and subsequently the tibia rotates or rolls about the joint to full flexion. Accordingly, the initial unlocking of the knee joint during flexion precedes actual full rotation of the knee.
Due to the above complexity of knee movement, for a knee brace to more fully support the knee joint of the user and facilitate rehabilitation and/or prevent re-injury of an injured knee joint, the brace must more closely analogize the movement of the knee than a simple hinge mechanism. Additionally, with specific relation to athletic or sports applications, the requirement for such analogized movement becomes acute. Further, for such sports applications, a knee brace must be relatively lightweight to avoid over-constriction which reduces success in the athletic endeavor, yet possess sufficient structural strength to adequately support the knee joint during impact thereupon.
In recognizing the need for an effective sports knee brace, various knee braces have been introduced into the marketplace. Such contemporary knee braces, however, have generally failed to provide the precise simulation of knee joint movement as described above or have comprised relatively heavy, bulky apparatus, thereby detracting from the user's athletic endeavor. Further, such contemporary designs have typically failed to possess sufficient structural integrity to prevent re-injury of the knee joint as may be occasioned by impact to the knee joint during physical sport endeavors.
Additionally, most contemporary sports braces have further been deficient in that the brace is not constructed in a manner so as to provide a consistently firm interface between the knee brace and the portion of the knee joint adjacent the crest of the tibia. This particular area of the knee joint typically becomes swollen after surgery or the occurrence of other trauma to the knee. As such, when the user is initially fitted with a knee brace, the knee brace is typically sized to conform to the shape of the knee at the time of the fitting. Thus, as the swelling of the knee subsides, oftentimes a gap is formed between the brace and the knee thereby necessitating that remedial measures be taken on the knee brace to alleviate the gap and achieve a more precise fit of the brace to the knee. Finally, most contemporary sports braces have further been deficient in their lack of providing suitable protection to the patella portion of the knee joint.